Avoid deferred engineering
Deferred design is not intended to defer engineering. The RPR is fully responsible for indicating required performance and engineering within the documents provided to the constructor. As indicated in Part 1 of this series, the concept of ‘design’ versus ‘engineering’ is critical in communicating what responsibility is being deferred to the constructor.
One example of inappropriate deferred engineering could occur if a structural engineer unintentionally omits critical annotations fully describing the size of steel members and the loads and eccentricities associated with connections between them. The final delegated design requirement from the constructor is the connection solutions provided by the steel fabricator based on the engineering information within the documents supplied by the structural engineer.
If information is omitted, the steel fabricator may become responsible for confirmation of the sizes of the steel members. However, this should not be the fabricator’s responsibility unless clear direction for that component is also provided through identification of any relevant engineering requirement in the specification documents.
Engineering (building code compliance) cannot be delegated. However, many professional design practices have inadvertently delegated engineering through the improper application of notes on drawings indicating a delegated design requirement without or with incomplete engineering direction, causing professional responsibility to the project to be questioned by contractors. Often, the ‘delegated design’ annotation is written on a drawing set by a well-meaning technologist that did not confer with the RPR. The RPR responsible for that component of engineering is the only person who can direct the need for delegated design.
Delegated design example
The following example shows even the best of intentions are not generally good enough when it comes to who decides what gets delegated.
In one case of unintentional delegated design arising from these authors’ own drawings, no loads were provided for the design of lightweight steel framing to support an aluminum storefront. When the constructor’s supporting design professional questioned the lack of engineering information, they were instructed to proceed based on their own design assumptions.
This essentially meant the RPR relinquished its commitment and assurance for compliance submitted to the authorities having jurisdiction (AHJs), an offense that could have resulted in loss of professional status for the licensed designer if a continued pattern showed failure to provide necessary information for the constructor. This could have been far worse if the structure had subsequently failed and caused harm to an individual.
Most registered architects and licensed interior designers continue to provide components as delegated engineering for items such as handrails and guards, tall partitions, and supporting metal fabrications, a practice that has become commonplace within the design community. However, this illustrates a similar lack of the engineering information necessary to complete the assignment of design responsibility to the constructor. These components are viewed as aesthetic, and do not receive the engineering input required to appropriately delegate.
Aesthetics cannot be delegated. Although this is not a building code compliance issue, there are similarities in this part of the discussion that will become more apparent when discussing assigned design in Part 3 of this series. When it comes to aesthetic components requiring input from a supporting registered professional, the RPR has an obligation to indicate the path for loads applied to these components, meaning details must contain information providing plausible sizes of members subjected to those loads. There must be clear indication of the expected level of finish contained on the drawings (showing extent, location, and sizes) and in the specification (describing quality of products and workmanship).
The extent of delegated design for these component types is usually restricted to design of the fastenings to structure (and seismic restraint in areas subject to earthquake loads). Comparatively, deferred design relating to pre-manufactured or pre-engineered components is covered under assigned design and design solutions provided by a supporting certified/qualified contributor. Handrail and guard loads are described in the building code and can be referenced as part of true delegated design, but the sizes of the members and path for transferring these loads shown on the drawings must be constructible while allowing for a design solution.
